fiberglass

Fiberglass is glass drawn or blown into extremely
fine fibers that retain the tensile
strength of glass while yet being flexible. The most used form is fused quartz, which when molten can be easily drawn
and which is resistant to chemical attack. Most often, the molten glass
is forced through tiny orifices in a platinum plate, on the far side of
which the fine fibers are united (though not twisted) and wound onto a suitable
spindle. Fiberglass mats (glass wool) are formed from shorter
fibers at random directions bonded together with a thermosetting resin;
they may be pressed into predetermined shapes. Fiberglass is used in insulation,
automobile bodies, etc.